Adjustable steering column assembly for a vehicle

Abstract: An adjustable steering column for a vehicle having a steering column (1) includes adjustment means, for example a clampable mechanism (4, 4A, 4B), to allow for reach adjustment of the steering column and for clamping the column at a desired reach position. Energy absorption means (5) are provided to absorb energy upon collapse of the steering column in a crash situation, there being a resilient-loaded pawl and ratchet mechanism (6, 7, 8) associated with the adjustment means, acting as a primary means in the crash situation to transfer energy from the column to the energy absorption means. A handle (9) acts both to clamp and unclamp the adjustment means and to bring the pawl and ratchet mechanism into and out of engagement.

Description: This invention relates to an adjustable steering column assembly for a vehicle. With steering columns which have a reach adjustable facility, i.e. a facility where the steering wheel can be adjusted towards and away from the driver for optimum comfort, there is also the need to ensure that, in a crash situation, energy transmitted through the steering column to an energy absorption system upon steering column collapse is transmitted satisfactorily. In other words, the reach adjustment means needs to remain locked, or substantially so, so that steering column collapse energy can be transmitted directly to the energy absorption means. GB-A-2 116 496 discloses an adjustable steering column assembly in accordance with the preamble of claim 1. US-A-4 793 204 also discloses an adjustable steering column and includes a tilt lock mechanism and a telescopic lock mechanism, both lock mechanisms including pawl and ratchet devices. According to the present invention, there is provided an adjustable steering column assembly for a vehicle, comprising a steering column, adjustment means to allow for reach adjustment of the column and for clamping the column at a desired reach position, energy absorption means to absorb energy upon collapse of said steering column in a crash situation, characterised in that the energy absorption means is mounted on a part of the vehicle and in that the steering column assembly further comprises a resiliently-loaded pawl and ratchet mechanism associated with said adjustment means acting as a primary means in the crash situation to transmit energy from the column to said energy absorption means, and being resiliently loaded for locking engagement. Preferably, there is a single actuating member to actuate said adjustment means and to bring the pawl and ratchet mechanism into and out of engagement. For a better understanding of the invention and to show how the same may be carried into effect, reference will now be made, by way of example, to the accompanying drawings, in which:- Figure 1 is a diagrammatic view of an adjustable steering column assembly for a vehicle, the assembly being shown in a normal condition in which the column is held in an adjusted position with pawl and ratchet mechanism engaged, Figure 2 is a view similar to Figure 1 but showing the condition of the assembly to allow free reach adjustment of the steering column, Figure 3 is a view similar to Figure 1 and showing a condition of the assembly at commencement of a crash situation in which the pawl and ratchet mechanism is not initially completely engaged, Figure 4 is a view similar to Figure 3 and showing the assembly in a crash situation with the pawl and ratchet mechanism engaged, Figure 5 is a diagrammatic side view of part of the steering column assembly and showing the pawl and ratchet mechanism, the adjustment means and the energy absorption means, and Figure 6 is a diagrammatic sectional view taken on the line VI-VI in Figure 5. Referring to the drawings, an adjustable steering column assembly for a vehicle is shown, including a steering column 1, a steering wheel 2, steering gear 3, adjustment means 4 to allow for reach adjustment of the column and for clamping the column at a desired reach position, and energy absorption means 5 to absorb energy upon collapse of the steering column in a crash situation. There are various possibilities for the actual construction of the adjustment means and the energy absorption means and the embodiments illustrated are merely by way of example. In the form illustrated, the adjustment means 4 is able to clamp the steering column 1 in a desired reach position by cam means 4A (Figure 6) which causes a bracket 4B of the adjustment means to clamp the steering column 1, the bracket 4B being coupled to the energy absorption means 5, which itself is mounted on a part of the vehicle. To ensure, in a crash situation, that energy of collapse of the steering column 1 is satisfactorily transmitted via the adjustment means 4 to the energy absorption means 5 whilst minimising the risk of steering column slip through the adjustment means, a pawl and ratchet mechanism is provided which is associated with the adjustment means 4. The mechanism includes a ratchet teeth block 6 which is fixed to part of the steering column 1, a toothed pawl 7, which is resiliently loaded towards the ratchet block 6 by a spring 8, and an actuating member in the form of a handle 9. The handle 9 is arranged to operate both the adjustment means 4, to clamp and release the adjustment means on the steering column 1 for reach adjustment, and the pawl and ratchet mechanism. The pawl 7 is pivotably mounted on a bolt 10 that is common to the adjustment means 4. Referring to Figure 1, the adjustable steering column assembly is shown in its normal condition with the adjustment means 4 clamping the steering column 1 in its desired reach position, the lever 9 being shown in its engaged position and the pawl and ratchet mechanism being shown engaged. It will be seen that the spring 8 is urging the teeth of the pawl 7 into the teeth of the ratchet block 6 and allowance is made for ± 10° free movement of the pawl 7. With the lever 9 in its disengaged condition as shown in Figure 2, the pawl 7 is taken out of engagement with the ratchet block 6 against the resilient bias of the spring 8 and the adjustment means is unclamped to allow for free smooth adjustment of the location of the steering wheel 2. Figure 3 shows the condition similar to Figure 1 but in a crash situation. It will be noted that, in this case, the reach adjustment of the steering column 1 has brought the assembly into a condition where, although the adjustment means is clamping the steering column, the teeth of the pawl 7 are riding on top of the teeth of the ratchet block 6. Of course, this makes no difference in a normal situation but upon crash the tendency will be for the steering column 1 to slip slightly through the clamped adjustment means 4 and this will then cause the ratchet block 6 to run over the pawl 7 so that the spring 8 rapidly engages the teeth of the pawl 7 with the teeth of the block 6 as shown in Figure 4. From that instant, energy of steering column collapse is transmitted directly through the locked pawl and ratchet mechanism to the energy absorption means 5, thereby allowing the energy absorption means to work alone to control as well as possible the collapse efforts during the crash.

Claims: An adjustable steering column assembly for a vehicle, comprising a steering column (1), adjustment means (4, 4A, 4B) to allow for reach adjustment of the column and for clamping the column at a desired reach position, energy absorption means (5) to absorb energy upon collapse of said steering column in a crash situation, characterised in that the energy absorption means (5) is mounted on a part of the vehicle and in that the steering column assembly further comprises a resiliently-loaded pawl and ratchet mechanism (6, 7, 8) associated with said adjustment means acting as a primary means in the crash situation to transmit energy from the column (1) to said energy absorption means, and being resiliently loaded for locking engagement. An assembly according to claim 1 and comprising a single actuating member (9) to actuate said adjustment means and to bring the pawl and ratchet mechanism out of engagement and to allow it under the resilient bias into engagement. An assembly according to claim 1 or 2, wherein said adjustment means includes cam means (4A) to clamp the steering column in a desired reach position, said cam means causing a bracket (4B) of said adjustment means to clamp the steering column. An assembly according to claim 3, wherein said bracket (4B) is coupled to said energy absorption means (5), which itself is mounted on a part of the vehicle. An assembly according to any one of the preceding claims, wherein said pawl and ratchet mechanism includes a ratchet teeth block (6) fixed to part of the steering column (1). An assembly according to any one of the preceding claims, wherein said pawl and ratchet mechanism includes a toothed pawl (7), which is resiliently loaded towards the ratchet mechanism.

Inventors: TOUSSAINT HERVE, TOUSSAINT, HERVE
Applicants: TORRINGTON CO, THE TORRINGTON COMPANY LIMITED
Application year: 1994
Main classification: B62D1
IPC codes: B62D1